Swollen Knee

What is knee swelling?

Knee swelling is a symptom that means there’s a buildup of fluid in or around your knee joint.

Your knee is the joint that connects your thigh bone (femur) to your shin bone (tibia) and kneecap (patella). It’s the biggest joint in your body. Your knees also contain cartilage, muscles, ligaments and nerves.

Anything that damages or irritates your knee can cause swelling. If you injured your knee or have a health condition that’s damaging the tissue around it, your knee can swell.

You might experience other symptoms if you have a swollen knee, including:

• Knee pain.
• Stiffness or tight feeling.
• Redness or discoloration.
• A feeling of heat or warmth.

You can start treating most causes of knee swelling at home with rest and over-the-counter (OTC) medicine. Visit a healthcare provider if you experienced a trauma or sports injury. See a provider if the swelling doesn’t get better in a few days, if you’re in severe pain or can’t move your knee.

What are the most common causes of knee swelling?

Healthcare providers classify knee swelling as traumatic or nontraumatic.

Traumatic knee swelling usually means you’ve experienced an injury. Sports injuries are the most common causes of knee swelling, including:

• ACL tears.
• MCL tears.
• Meniscus tears.
• Hyperextended knees.
• Sprains.
• Bone fractures.
• Dislocations.
• Patellofemoral pain syndrome (PFPS).

Nontraumatic knee swelling is usually caused by arthritis. Degenerative arthritis (osteoarthritis) and inflammatory arthritis (including rheumatoid arthritis and psoriatic arthritis) can cause swelling.

Other health conditions that can cause nontraumatic knee swelling include:

• Autoimmune disorders.
• Infections.
• Bursitis.
• Tendinitis.

How do you treat a swollen knee?

How you treat knee swelling depends on which type you have. Visit a healthcare right away if you experienced an injury or trauma.

You can initially treat nontraumatic knee swelling at home. Don’t play sports or do any activity that can put more stress on your knee. Over-the-counter pain medications like NSAIDs (nonsteroidal anti-inflammatory drugs) or acetaminophen can relieve pain and reduce inflammation. Talk to a healthcare provider before taking pain relievers for more than 10 days in a row.

Follow the RICE method as soon as you notice pain or other symptoms:

• Rest: Avoid the activity that caused your injury. Don’t overuse your knee while it heals.
• Ice: Apply a cold compress or ice packs wrapped in a thin towel to your knee for 15 minutes at a time, a few times a day.
• Compression: You can wrap your knee in an elastic bandage to help reduce swelling.
• Elevation: Prop your knee and leg up above the level of your heart as often as you can.

A healthcare provider might suggest other treatments if you have a specific injury or health condition. You might need:

• Crutches.
• A brace that holds your knee in place.
• Physical therapy.
• Corticosteroids.

Surgery for knee swelling

Most people who experience knee swelling don’t need surgery. If the swelling is the result of an injury like a torn ligament or meniscus tear, you might need a knee arthroscopy to repair the damage inside your knee.

Your provider might recommend a knee replacement (arthroplasty) if you have arthritis and symptoms like swelling and pain in your knee make it hard (or impossible) to participate in your daily routine. Your provider will usually only suggest surgery if other treatments don’t relieve your symptoms.

If you need knee surgery, your provider or surgeon will tell you what to expect and how long it will take to recover.

How can you prevent knee swelling?

During sports or other physical activities:

• Wear the proper protective equipment.
• Don’t “play through the pain” if your knee hurts during or after physical activity.
• Give your body time to rest and recover after intense activity.
• Stretch and warm up before playing sports or working out.
• Cool down and stretch after physical activity.

Follow these general safety tips to reduce your risk of an injury:

• Make sure your home and workspace are free from clutter that could trip you or others.
• Always use the proper tools or equipment at home to reach things. Never stand on chairs, tables or countertops.
• Use your cane or walker if you have difficulty walking or have an increased risk of falls.

When should I see a healthcare provider with a swollen knee?

Visit a healthcare provider if you experience trauma or injury. See a provider if you have non-traumatic swelling and at-home treatments don’t improve your symptoms in a few days.

Go to the emergency room if you experience any of the following:

• Severe pain.
• You can’t move or use your knee.
• Major trauma like a fall from height (like off a ladder) or a car accident.

What should I do if my knee is swollen after running?

Exercise can be stressful on your joints, especially if you suddenly work out harder than usual. If your knee is swollen after a long run, follow the RICE method (Rest, Ice, Compression, Elevation). Don’t “play through the pain” or keep running if you’re sore and have a swollen knee.

Replace your running shoes every six to nine months (or after you’ve walked or run between 250 and 500 miles in them).

Visit a healthcare provider if your symptoms don’t get better after a few days of at-home treatments.

A note from Cleveland Clinic

A swollen knee can be annoying, especially if it causes other symptoms like pain or stiffness. But don’t ignore your symptoms. Visit a healthcare provider if you didn’t experience trauma or injury, but swelling is getting worse or doesn’t go away in a few days. They’ll help you understand what’s causing the swelling, how you can treat it and what you can do to avoid it in the future.